code: def test_create_doc_underscore():
      doc = Mock()
      doc.doc = doc
      uscore = Underscore(Underscore.doc_extensions, doc)
      assert uscore._doc is doc
      assert uscore._start is None
      assert uscore._end is None
  
file_path: spacy/spacy/tests/doc/test_underscore.py
imports: import pytest
  from mock import Mock
  from spacy.tokens import Doc, Span, Token
  from spacy.tokens.underscore import Underscore
label_desc: Use image node_id 2 for calling a global function with example usage: test_create_doc_underscore() without return types